Coating compositions based on a mixture of an active hydrogen-containing material, a beta-hydroxy urethane and a cure catalyst have been employed for priming and painting vehicles and other substrates. The beta-hydroxy urethane typically is prepared by reacting an isocyanato compound with a 1,2-polyol, or by reacting a primary or secondary amine with a carbonate. These reactions can produce a so-called “blocked isocyanate” in which the isocyanate groups are replaced by pendant hydroxyalkyl groups. The blocked isocyanate is stable if properly handled and stored (typically even in the presence of an active hydrogen-containing material). On heating the hydroxyalkyl groups will unblock to liberate the isocyanate groups which can then react with the active hydrogen-containing material.
Unfortunately some blocked isocyanates have been formulated in solvents that are now regarded as Hazardous Air Pollutants (“HAPs”). This limits the use of such blocked isocyanates and may necessitate their reformulation.